Math Contest 4/16

Mowing Lawns Ron and Darrell mow lawns to earn money in the summer. Ron has a riding mower. He charges $18 a yard and pays his little brother $7 to help. He is able to do 9 yards in a day. Darrell has a walking mower. He charges $20 a yard and does 8 yards a day. Who do you think does better? Explain your answer.

Mowing Lawns Answer Ron charges $18 a yard but only clears $11 since he pays his brother $7. Ron will make 9 x $11 a day so clears $99. Darrell clears $20 a yard and though he only completes 8 a day he makes 8 x $20 so clears $160 a day. Darrell clearly is doing better.

Turkey Time Julia Child was roasting a turkey. It has been out of the oven for 20 minutes. The turkey was roasting for 4 hours and 15 minutes. The oven was preheated for 10 minutes. If it is 5:00 now, then what time did Julia put the turkey in the oven?

Turkey Time Answer Count backwards! Start at 5:00 count back 20 minutes to 4:40. Count back 4 hours and 15 minutes to 12:25. The time for preheating does not matter! So the answer is 12:25!

Jumping Frogs A frog jumped on several stones on his way to the pond. He did not land on the same stone twice. The product of all of the stones that he hopped on was 19,635. On which stones did he jump?

Jumping Frogs Answer Think prime numbers! 3 x 5 x 7 x 11 x 17 = 19635.

Multiplication Madness Use multiplication to solve these arrays:

Multiplication Madness Answer

Birthday Beach Bash Twins Maggie and Dana and their friend Rebecca were celebrating their tenth birthdays with a party at the beach. The first fun activity was water games. As Chelsea arrived, she observed that 1/3 of the kids were playing with beach balls, 40% were exploring underwater with goggles, and .25 were floating on tubes. The party continued with many games, presents, and the ever popular cake and ice cream. When the party was over, each kid received a party bag and a balloon to take home. There were even 3 left for Maggie, Dana, and Rebecca. How many balloons were needed for the beach party?

Birthday Beach Bash Answer First convert - she observed that 1/3 of the kids were playing with beach balls, 40% were exploring underwater with goggles, and .25 were floating on tubes to fractions. 1/3, 40% to 2/5 and .25 to 1/4. Next find the lcd for the 3 fractions which is 3 x 5 x 4 = 60 so that you can find the actual number of people who are attending the party by writing fractions for each group. Rewrite the fractions to 20/60, 24/60, and 15/60. If you add the fractions you will get 59/60 and if you add 1/60 for Chelsea who observed the fractional makeup of party activities you will get 60/60 people who were asked to the party. If you add in the 3 for whom the party was given you will see that 63 balloons were needed.